1. Field of the Invention
The present invention relates to a packaging bag, which is formed in the shape of pillow or envelope and is provided at its crease portion on the side of the packaging bag with a plurality of tearable portions through which the packaging bag can be opened.
2. Description of the Related Art
As a packaging bag for receiving oily food such as fried pastry, there has recently been used a packaging bag formed in the shape of pillow or envelope. The packaging bag has on its bask surface side a heat sealed portion formed by heat-sealing the opposite ends of a strip film. The packaging bag is filled with an inert gas such as nitrogen gas in the light of prevention of oxidation of contents received in the packaging bag. Such a packaging bag is required to have a high sealing strength, for example, a sealing strength of 3.5 kg/15 mm width (i.e., the sealed portion having a width of 15 mm can resist a peeling force of 3.5 kg) in order to ensure a high gas-barrier property.
However, with such a high sealing strength, a strong force is required to unseal the packaging bag, thus making it impossible to carry out a smooth opening. Accordingly, there has been proposed to reduce the sealing strength to 1.2 kg/15 mm width. It is however hard to adjust properly the sealing strength upon manufacturing of the packaging bag with the result that the packaging bag having the desired sealing strength cannot be manufactured in a reliable manner.
In view of the fact that the smooth opening cannot be carried out in the above-described packaging bag having the heat-sealed portions, there has been proposed a packaging bag having on its upper and lower sealed portions zigzag notches, respectively. The zigzag notches serve as tearable portions from which the packaging bag can be torn to open the same. However, the sealed portions of such a kind of packaging bag have a relatively large thickness, and it is not easy to tear them even when the zigzag notches are formed thereon. Moreover, the packaging bag is torn in its longitudinal direction, and the contents received therein tend to be scattered when tearing the packaging bag.
In addition, in case that the packaging bag receives oily food such as fried pastry, decrease in an amount of the contents requires fingers to be stuck deeply into the packaging bag to pick the contents therefrom. As a result, oil adheres not only to the fingers, but also to the palm and back of the hand, thus giving a person an unpleasant feeling.